These projects examined the effects of varying levels of forest disturbance on ectomycorrhizal communities and mushroom fruiting.  Ectomycorrhizae (ECM) are symbiotic fungi on tree roots.  These fungi extend into the soil to share nutrients and water with the tree, and can protect the tree against stresses such as diseases and toxic metals.  Since ectomycorrhizae are critical to forests, we wanted to examine how sensitive ECM communities were to a range of forest disturbance levels.  Future projects will address questions on the role of ECM diversity to tree growth and health, and the functional significance of below-ground linkages to tree growth.

Ectomycorrhizal outer mantle with cystidia (1000x)

A second issue concerning ECM is the commercial value of their mushrooms, such as the pine mushroom (Tricholoma magnivelare), the golden chanterelle (Cantharellus formosus) and the king bolete (Boletus edulis).  As ECM mushrooms, these species are sensitive to timber harvesting.  We have examined the effects of small gaps and partial cutting on ECM mushroom diversity and biomass.  These studies help explore options forest managers will have in managing the landbase for timber and commercial mushrooms.

Cantharellus formosus

Available Literature:

Kranabetter, J.M. and Wylie, T. 1998. Ectomycorrhizal community structure across forest openings on naturally regenerated western hemlock seedlings. Can. J. Bot., 76:189-196.

	Abstract: We examined the diversity and distribution of ectomycorrhizal morphotypes on naturally-regenerated western hemlock (Tsuga heterophylla (Raf.) Sarg.) seedlings across small forest openings (50-75 m diameter) in northwest British Columbia. The total and average morphotype richness decreased across the 4-year-old forest openings despite the rapid establishment of western hemlock and lack of soil disturbance. Average fungal richness decreased from 13.1 morphotypes under theforest canopy to 9.6 at the forest edge (27% reduction) and to 7.8 in the forest opening (40% reduction). Cenococcum geophilum, Mycelium radicis
Ectomycorrhizae on hemlock root tip	atrovirens and Lactarius spp. were the most abundant ectomycorrhizae at each gap position; none of the
ectomycorrhizal fungi found in openings were eliminated by ‘late-stage’ fungi in mature stands. This fungal distribution supports the ‘multi-stage’ concept of ectomycorrhizal succession. Seedlings under the forest canopy had a total of 38 fungal morphotypes in a relatively even distribution pattern that corresponded well to the 'random niche boundary' hypothesis. Fungal distributions were progressively less even for seedlings at the forest edge and opening than for seedlings beneath the canopy, perhaps because reduced fungal diversity and hyphal inoculum had affected the competitive balance of the ectomycorrhizal community.

Kranabetter, J.M., Hayden, S. and Wright, E.F. 1999.  A comparison of ectomycorrhiza communities from three conifer species planted on forest gap edges.  Can. J. Bot. 77: 1193-1198.
Abstract: We examined the ectomycorrhiza communities on lodgepole pine (Pinus contorta var. latifolia), white spruce (Picea glauca), and subalpine fir (Abies lasiocarpa) seedlings planted together on mature-forest edges in north-western British Columbia.  We examined 32 seedlings of each tree species, grouped by pairs along the north and south edges of 8 gaps.  We found 74 morphotypes in total, with an average of 52 morphotypes per tree species.  Morphotypes with emanating hyphae or strands made up 60% of the overall ectomycorrhiza community.  Multi-host fungi averaged almost 60% of total morphotypes in species comparisons, although some of the multi-host fungi appeared to have tree host preferences.  The average community similarity, based on morphotype abundance, was 52% between conifer species, and 37% for morphotypes with emanating hyphae or strands.  Within planted groups, between seedlings 1 to 2 m apart, community similarity ranged from 2 to 40% for morphotypes with emanating hyphae or strands.  In mature, mixed forests, the infrequent occurrence of many multi-host ectomycorrhizae created a wide range in the probability of hyphal linkages between neighbouring seedlings.

Kranabetter, J.M. 1999.  The effect of refuge trees on a paper birch ectomycorrhiza community.
Can. J. Bot. 77: 1523 - 1528.
Abstract:  Live trees within forest disturbances could support refugia populations of ectomycorrhiza fungi from which to reestablish ectomycorrhiza communities during forest succession.  I examined the effectiveness of refuge paper birch trees (Betula papyrifera) in maintaining a forest ectomycorrhiza community on birch seedlings, both in clearcuts and forests, in northwest British Columbia.  Seedlings next to refuge birch trees in clearcuts had equal levels of average morphotype richness and eveness as seedlings next to mature birch trees in forests.  Seedlings outside of the rooting zone of refuge trees had significantly less average morphotype richness in both clearcuts and forests, decreasing by 38% and 15%, respectively.  The ectomycorrhiza communities were also more unique (lower community similarity) next to refuge trees than for seedlings away from refuge trees, especially in clearcuts.   These treatment effects could be explained by differences in the ability to disperse and establish between early-stage, multi-stage, and late-stage ectomycorrhiza fungi.  The results suggest refuge trees would be effective in forest management as sources of inocula for multi-stage and late-stage fungi.

Kranabetter, J.M. and P. Kroeger. 2001.  Ectomycorrhizal mushroom response to partial cutting in a western hemlock/western redcedar forest. Can. J. For. Res. 31: 978-987.
Abstract:  We examined epigeous ectomycorrhizal mushroom richness and productivity five years after partial cutting in a western hemlock (Tsuga heterophylla) - western redcedar (Thuja plicata) forest of northwestern British Columbia.  Mushrooms were collected throughout the fruiting season (July to October) for three years from plots with mesic soil conditions and residual basal areas ranging from 23 to 69 m²/ha for western hemlock, and 0 to 26 m²/ha for western redcedar.  Partial cutting had no apparent effect on mushroom phenology over the three years.  Significant block interactions demonstrated that reductions in basal area of western hemlock could lead to positive, neutral and negative responses in mushroom richness, biomass and number of fruiting bodies.  These responses were related to stand structure and the potential differences in tree vigour after partial cutting.  In addition, there was weak evidence that western redcedar, a host for vesicular-arbuscular mycorrhiza, had a negative effect on average taxa richness.  The study demonstrated that partial cutting systems could allow some timber removal without necessarily reducing ectomycorrhizal mushroom communities.
 
 

Durall, D.M., Jones, M.D., Wright, E.F., Kroeger, P., and Coates, K.D. 1999. Species richness of ectomycorrhizal fungi in cutblocks of different sizes in the interior cedar-hemlock forests of northwestern British Columbia: sporocarps and ectomycorrhizae. Can. J. For. Res. 29: 1322-1332. Abstract: We investigated the species richness of ectomycorrhizal  fungi based on epigeous sporocarps in an Interior Cedar-Hemlock forest in northwestern British Columbia in gap sizes of 49 to 4526 m2  three to four years following harvest.  We also determined ectomycorrhizal diversity on Pinus contorta var. latifolia and Tsuga heterophylla seedlings two years after out-planting.  Ectomycorrhizal fungal richness, based on epigeous sporocarps, decreased exponentially as gap size increased. There were sporocarps of 15 species along 475 m of transect in gaps larger than 900 m2, which was approximately 13% of the number of species present in neighboring forests (115 species along 300m of transect).
These data have implications for foresters who would be interested in managing forests for	Boletus mirabilis
both timber and edible mushroom harvesting.  Ectomycorrhizal richness on seedlings decreased slightly at increasing distances from the edge of the intact forest.  The maximum richness was found at 7 m or less from the forest edge for both tree species.  The decrease in richness with distance from the forest was associated with an increase in the proportion of Thelephora mycorrhizae in the samples.  The number of types of ectomycorrhizae on root systems and the number of species producing epigeous sporocarps were not correlated.  These results confirm the importance of sampling both sporocarps and root tips to achieve an accurate estimate of the ectomycorrhizal fungal community in forest ecosystems.

J.M. Kranabetter and J. Friesen 2002. Ectomycorrhizal community structure on western hemlock (Tsuga heterophylla) seedlings transplanted from forests into openings. Can. J. Bot. 80:861-868.
 Abstract:  This study tested whether mature-forest ectomycorrhizal (ECM) communities could be maintained in forest openings on seedlings.  Naturally-regenerated western hemlock (Tsuga heterophylla) seedlings were transplanted from mature forests into openings and the ECM fungal community was compared after two years with similar seedlings planted back into the forests, or seedlings from openings planted back into openings.  Fewer ECM morphotypes, lower average richness per seedling, and a steeper, less even species distribution curve were found, all of which suggest the mature-forest ECM fungal community changed after transplanting forest seedlings into the openings.  The increased abundance of pioneer fungi such as Thelephora terresteris suggested many of the mature-forest ECM fungi were unable to maintain or continue root colonization in openings.  Results suggest many mature-forest ectomycorrhizal fungi require further stand development to maintain enough rooting density and hyphal contact to persist.

Kranabetter, J.M. 2004. Ectomycorrhizal community effects on hybrid spruce seedling growth and nutrition in clearcuts. Can. J. Bot. 82: 983-991.
Abstract:  A diverse community of ectomycorrhizal fungi is generally considered beneficial to forest ecosystems, but the function of ectomycorrhizal communities should be considered within an ecological context.  The growth of hybrid spruce (Picea glauca x sitchensis) seedlings were compared after transplanting into recent clearcuts, where soil moisture and nitrogen are typically readily available.  The seedlings had either a 'forest' ectomycorrhizal community (taken from forest gap edges) or a 'pioneer' ectomycorrhizal community (taken from disturbed road edges) and were planted at wide and close spacing.  After three years, there was considerable overlap in morphotype distribution and abundance (64% community similarity between 'forest' and 'pioneer' seedlings), but height growth was 25% greater for the 'pioneer' seedlings.  There was a reduction in diameter at close spacing, with little difference in competition effects between ectomycorrhizal communities.  There were no differences detected in foliar nitrogen concentrations, and no evidence of nitrogen or phosphorus deficiencies.  The advantage of fungi such as Amphinema byssoides, Thelephora terrestris and Laccaria laccata might be the proliferation of fine roots that allows for the fullest utilization of abundant soil resources.  The results suggest that the ectomycorrhizal communities arising after clearcut disturbances are well adapted to these initial soil conditions.

Kranabetter, J.M. 2005.  Understory conifer seedling response to a gradient of root and ectomycorrhizal fungal contact. Can. J. Bot. 83: 638-646.

 Abstract:  The possible benefit of common mycorrhizal network (CMN) linkages to seedling growth was tested in a low light partial-cut forest understory.  Naturally-regenerated western hemlock (Tsuga heterophylla) and hybrid spruce (Picea glauca x Picea sitchensis) seedlings were transplanted directly into soil or within bags of different pore sizes to restrict the amounts of root and ectomycorrhizal contact.  The 5 year study included ‘full contact’ (no bag), ‘moderate contact’ (250 µm openings) and ‘low contact’ (4 µm openings) treatments.  Height increment was lowest for full contact seedlings over most of the experiment, and highest for low contact seedlings by years 4 and 5.  Full contact seedlings also had slightly lower foliar N content than moderate and low contact seedlings.  There were no significant interactions in growth detected between tree species and treatments, despite the higher potential for CMN linkages between a western hemlock understory and canopy.  Fifty-eight ectomycorrhizal fungal morphotypes were identified on the seedlings, including many with smooth mantles or with only sparse emanating hyphae, which likely reduced the potential for CMN linkages.  These results would support the more traditional concepts of competition for scarce resources by isolated seedlings as the primary interaction for the understory of these mature forests.